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Dec 1st, 2008

Help, Im trying to implement my own strcpy

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C++ Syntax (Toggle Plain Text)
void StrCpy(char * Dest , char* Src )
{
 
  while(*Src){
    *Dest = *Src++;
    cout << *Dest ++;    
 
  }
}
 
void main()
{  
 
char* string1 = "\0";
char * string2 = "EL";
 
StrCpy(string1, string2);
//cout << string1; //must output EL
}
void StrCpy(char * Dest , char* Src )
{
 
  while(*Src){
    *Dest = *Src++;
    cout << *Dest ++;    
    
  }
}

void main()
{  

char* string1 = "\0";
char * string2 = "EL";

StrCpy(string1, string2);
//cout << string1; //must output EL
}

Im trying to output EL after its copied to string1 but nothing its printed

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namehere05

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Dec 1st, 2008

Re: Help, Im trying to implement my own strcpy

You are attempting to stuff 3 bytes (string2) into a character array that is only 1 byte (string1). Try this:

(Toggle Plain Text)

int main()
{  

char string1[4] = {0}
char * string2 = "EL";

StrCpy(string1, string2);
//cout << string1; //must output EL
}

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Re: Help, Im trying to implement my own strcpy

it works!! .. and I heard of that before but got confused cuz the thing I did was to Initialize char * string1 = "longer than string2" and evrything else the same and it didnt work either so I thought that wasnt the problem as I thought there was a solution without need to "mix" char[] and char *
Could you tell me why using a longer string than string2 to initialize char* pointer wouldnt work in my method
I thought I would get something like this:

char* string 1 = "longer than string2"
char* string 2 = "NONSENSE"

func(string1 string2)//same as before
cout << string1 ; //I was expecting it to print changed string1 as
"NONSENSEhan string2"
in other words overwritting

namehere05

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Dec 2nd, 2008

Re: Help, Im trying to implement my own strcpy

>>I did was to Initialize char * string1 = "longer than string2" and evrything else the same and it didnt work either
I didn't work because you can't change string literals, which is what you attempted to do. But you could have done it like this:
char string1[] = "longer than string2" , which will put the text in writeable memory.

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Re: Help, Im trying to implement my own strcpy

Click to Expand / Collapse Quote originally posted by Ancient Dragon ...

>>I did was to Initialize char * string1 = "longer than string2" and evrything else the same and it didnt work either
I didn't work because you can't change string literals, which is what you attempted to do. But you could have done it like this:
char string1[] = "longer than string2" , which will put the text in writeable memory.

I thought you could always assign a char* to another char*. Are you sure that declaring

C++ Syntax (Toggle Plain Text)

char* string1 = "Bigger than String2";

wont work?

Agni

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Dec 2nd, 2008

Re: Help, Im trying to implement my own strcpy

And in other news, reports are coming in from all over the web about the same thing happening elsewhere.

Experts agree that there is only one possible solution.

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Re: Help, Im trying to implement my own strcpy

OK.. my bad... True .. it will not work.

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Re: Help, Im trying to implement my own strcpy

well thank you all for answering.
"and in other news".. I know .. "Have the feeling" its been answered tons of time but kinda not my fault;
I cheked many introduction texts about that and they dont say how they (the [] and the char * or the string class declarations) happend to be related.
they teach either one and/or the other as independent but not how they in this case "mix"; the do's and dont's are either one declartion or another weighted

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Re: Help, Im trying to implement my own strcpy

Remember the K&R masterpiece:

c Syntax (Toggle Plain Text)
while (*dest++ = *src++);
while (*dest++ = *src++);

Unforgettable Algol 68's genes are still alive in C and C++

...

Last edited by ArkM; Dec 2nd, 2008 at 8:25 am.

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Re: Help, Im trying to implement my own strcpy

Click to Expand / Collapse Quote originally posted by ArkM ...

Remember the K&R masterpiece:
c Syntax (Toggle Plain Text)
while (*dest++ = *src++);
while (*dest++ = *src++);
Unforgettable Algol 68's genes are still alive in C and C++ ...

can I just add, you need to remember to add a
*dest=0; line after the while. You will need something similar in any of the other posts.

Last edited by Ancient Dragon; Dec 2nd, 2008 at 9:32 am. Reason: corrected icode tag

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